Gravity (2013) is hugely entertaining. People love it and Sandra Bullock does a great job. It's the The Perils of Pauline (1947) crossed with Apollo 13 (1995) - a great sequence of disasters that she somehow, through her own resourcefulness, triumphs through. It could be set in a haunted house or a burning building or a flooding cave or a post-apocalyptic New York. It doesn't really matter. The visuals are what really sells it. They are phenomenally good. Better than ever. "Gravity" gets the visuals right. It's just like being there on a spacewalk. 2001: A Space Odyssey (1968) was a much more thought-provoking juxtaposition of reality and art.

I am not a thrill seeker. I never want to feel fear. Fear for me is taking a random chance to get my body to put chemicals into my blood to make me feel alive. I don't want to do that. I feel pretty alive as it is. I feel far more alive when I am managing something that is really complex: a risk, or a machine trying to solve a problem that is really hard. That makes me feel alive, not just exciting the nerve endings. So, fear for me means I made a mistake. It means I didn't know what I was doing.

[2013, on a perceived decline in the role of NASA] NASA launched a probe to Mars. They have 'Curiosity' driving around Mars. They have 'New Horizons' on the way to Pluto right now. We have a probe orbiting around Mercury for the first time. We have dozens and dozens of probes around the earth. We have stuff going around the moon. We have stuff studying our upper atmosphere. And we have a crew permanently on orbit on a space station that NASA built and runs. And yet, because people who don't pay really close attention to it, don't get to see a shuttle launch every six weeks - they think NASA has been cancelled. Really?

People have no idea how far away Mars is. Half the time it's the other side of the sun from us. That's a long ways away. It's like saying in 1493 'Hey, I want to fly across the Atlantic. Why can't we fly across the Atlantic?'... We are sort of in that state of confusion between the reality of technology and the desire of science fiction. Our technology cannot take us safely to Mars and back right now. Right now we have just the technology to safely go to the space station and back.

[response to William Shatner's inquiry, "Are you tweeting from space?"] Yes, standard orbit, Captain. And we're detecting signs of life on the surface.